I have been getting some odd eggs...

Over the last couple of weeks I have found some weird eggs! My girls have access to lots of grit. I did accidentally pick up crushed granite (I think) instead of my usual oyster shell. Could that make a difference? They are on 16% layer.
Don't know which of my girls lay this speckled, coppery one. This one is even had creases on the pointy side.

Young ones can lay all sorts of odd eggs as their systems are getting used to laying. However, if this just started happening after you stopped offering oyster shell, there could be a link. Some chickens seem to do fine with the calcium level in the layer feed, but some need a little extra on the side.

There is also some article that someone on here has linked to before about the reasons for some oddness in eggs. It's not always lack of calcium. One of mine laid a couple of strange wrinkled eggs that looked like tufted pillows when she was young.

They need free access to both grit and oyster shell, fwiw. If you don't have oyster shell on hand right now, you can give them back crushed up egg shell and that will help some. Unless it's at the beginning of the laying cycle, rubber eggs are usually an indicator or low calcium. Fwiw....

Hens should always be offered both oyster shell calcium and a good quality grit to keep them healthy and productive.
Oyster shell to ensure good hard shells and grit to digest their food, otherwise they could possibly starve to death.

Calcium/Oyster Shells
If your hens have a good, "complete" layer feed, they may not ever need oyster shells or any supplemental calcium! However, it never hurts to offer it free choice (and it is inexpensive and lasts a long time). The reason is that some flocks that spend most of the day foraging, or are given too many treats, in which case they don't get all the calcium they need from their feed. This can cause weak or irregularly shaped eggs, slow laying and can even cause behavior problems like egg-eating, because they're so desperate for the calcium they need! (We recommend you cut down on the treats, too!)

Grit
Ever heard the saying "scarce as a hen's teeth"? That's right, chickens don't have them! Instead they eat tiny pebbles and store them in their "crop". When the food enters their crop, the pebbles grind it up to make digestion easier. For baby chicks, sand, parakeet gravel or canary gravel, available at your local pet store or grocery store pet aisle, will suffice. You can either sprinkle this in their feed or provide it in a small cup or bowl.